Commutator for dynamo-electric machines.



P. w. YOUNG.

GOMMUTATOB FOR DYNAMO ELECTRIC MACHINES.

rum-non FILLED JULY 19, 1909.

947,768. Patented Jan. 25,1910.

- r Flg- 4 ll 2 a 2 f; a a 2 1 J Witness 6 s; Inventor, W hag g4 Frederick W Yo'zm W (a @Q I y i FREDERICK WILLIAM YOUNG, OF EAST ORANGE, NEW JERSEY.

GOKMUTATOB FOB. DYNAMO-ELECTRIC MACHINES.

Specification of Letters Patent.

Patented Jan. 25, 19,10.

Application filed July 19, 1909. Serial No. 508,346.

To all whom it may concern: I

Be it known that I, FREDERICK WILLIAM YOUNG, a citizen of the United States of America, and aresident of East Orange, county of- Essex, and State of New Jersey, have invented certain new and useful Improvements in Commutators for Dynamo- Electric Machines, of which the following is a specification.

My invention relates to a commutator in which adjacent to the sides of each bar at which the circuit is broken with the brush, there is placed a zigzag folded metallic strip in contact with the bar which continues in contact with the brush after the bar has left the brush. and serves to introduce resistance before the circuit is completely broken between the bar and the brush. The object of the invention is thereby to improve the commutation by reducing the tendency to s ark and preventing the commutator bars rom burnlng.

A further object of the invention is to provide this resistance in a structure which is wholly integral with the commutator.

A further object of the invention is to grade the resistance in a series of ste s of such value that the current will be re need in a series of substantially equal steps.

In the accompanying sheet of drawings, which forms a part of this application- Figure 1 is a perspective of a portion of a commutator embodying my invention with a composite zigzag folded metallic strip, one of the strips being partly opened. Fig. 2 is a perspective to a smaller scale of one of the composite strips of Fig. 1 before folding, arranged to suitably grade the resistance. Fig. 3 is a perspective of a strip in which the resistance is suitably graded by varying the width at different points along the strip. Fig. 4 is a perspective of a strip which is not graded.

The commutator is composed of the usual copper bars 0 a which are provided with stems s s for connection with the coils of the armature in the usual manner. On each side" of each bar is a zi zag folded metallic strip r for which I fin copper of a thickness of five one-thousandths to thirty-five one-thousandths of an inch suitable, but do not confine myself to copper, as high resist ance metal such as phosphor bronze of German silver may be substituted. This is folded back and forth on itself in azigzag, making each section between folds about equal to the length ofa commutator bar. The strip is preferably constructed so as to have an increased conductivity near the end which is in contact with the commutator bar so that the current will be cut down in a more uniformly graded manner as the sections of the strip pass out from under the commutator brush. This grading may be effected by thickening the strip at one end, as by laying short strips 6 t on it as shown in Figs. 1 and 2, or by varying the depth of the strip as shown in Fig. 3. Strips of mica m m are laid between the folds of the strip and between adjoining strips in contact with adjoining commutator bars.

As illustrated the folded strip is placed on each side of each bar to provide for both directions of rotation. If it is intended to havethe commutator rotate in but one direction it is only necessary that the strip be on the side of each bar which'is the last to pass from under the brush.

What I claim as new, and desire to secure by Letters Patent of the United States, is-

1. In a commutator, the combination with a commutator bar of a zigzag folded metallic strip in contact with the bar which forms a continuation of the contact surface of the bar and in which the several folds are separated by insulation, substantially as described.

2. In a commutator the combinationwith a commutator bar of a zigzag folded metallic strip in contact with the bar which forms a continuation of the contact surface of the bar, in which the conductivity of the several folds is decreased from the end in contact with the bar toward the end which is remote from the bar, and in which the several folds are separated by insulation, substantially as described. I

3. In a commutator, the combination with a commutator bar of a zigzag folded metalthe several parts are separated by insulation, lic strip in contact with the bar which forms substantially as described. 10 a contlnuation of the contact surface of the Signed at East Orange, New Jersey, the bar, in which the folds adjacent to the bar 16th day of July, 1909.

have a plurality of layers formed of a plll- FREDERICK WILLIAM YOUNG. rality of strips in contact, and the number 4 .lvltnessesz of such layers is diminished toward the end CLARENCE N. WHEELER,

' which is remote from the bar, and in which HERBERT C. PETTY. 

